Air pollution in Delhi reached "severe" levels on Wednesday with an overall air quality index (AQI) of 422 at 6 am, choking residents and cloaking the city in thick smog. Air pollution is a risk for all-cause mortality as well as specific diseases. It includes stroke, ischaemic heart disease, chronic obstructive pulmonary disease, lung cancer, pneumonia, and cataract (household air pollution only).  

While the adverse effects of air pollution on respiratory and circulatory systems are well-documented, a deeper and more alarming impact has now come to light—its perilous effect on renal function. The kidney, a critical organ for filtration, bears a heavy burden from environmental pollutants, making it especially vulnerable to damage.

In developing nations, exposure to pollutants remains a significant cause of kidney disease, contributing to the global health crisis. Astonishingly, up to 22% of the global disease burden and nearly a quarter of deaths are linked to environmental pollution, underscoring its pervasive reach.

Research has linked long-term exposure to particulate matter (PM2.5)—tiny particles less than 2.5 micrometers in diameter—to an increased risk of membranous nephropathy, a severe kidney condition that damages renal filters, leading to massive protein leakage into the urine.

In a groundbreaking study published in the Journal of the American Society of Nephrology, air pollution has been implicated in the onset of chronic kidney disease (CKD) and its rapid progression to dialysis. The study monitored over 2.5 million US veterans without prior kidney disease for 8.5 years. Pollution data was meticulously tracked using advanced monitoring from the Environmental Protection Agency (EPA) and NASA.

The findings are alarming; every 10 micrograms per cubic meter increase in air pollution led to a 25–37% rise in new CKD cases, a 36% surge in rapid renal function decline, and a 31% spike in kidney failure requiring dialysis. Researchers estimated that pollution during the study period was responsible for approximately 45,000 new CKD cases and over 2,400 dialysis patients.

Supporting evidence from Taiwan, Korea, and Europe reveals a consistent pattern. Higher levels of air pollution, especially particulate matter (PM2.5) and sulfur dioxide (SO2), were associated with reduced kidney function and an elevated risk of CKD. Short-term pollution exposure even resulted in measurable declines in estimated glomerular filtration rate (eGFR), a key indicator of kidney health.

In India, the kidney disease crisis is growing. Data from the Indian Society of Nephrology indicates that 16% of CKD cases stem from unknown causes. Experts now speculate that air pollution may play a significant role in these unexplained cases.